This invention relates generally to improvements in lifting devices, and more particularly to a flexible hoist ring assembly for moving, loading, suspending, or lifting material and equipment during outfitting of a ship under construction. This invention gives the individual user the flexibility to quickly install a safe temporary lifting point when and where needed, thereby minimizing delays especially those resulting from waiting for support personnel.
In the prior art, when the need arises to provide a lifting point during construction, a portable clamp is installed by attaching the clamp to overhead structure. However, when location does not permit the use of a clamp, a lifting pad is installed. This pad is generally a 75 mm.times.75 mm piece of steel plate having a hole in the center. The plate is welded along one edge to structure overhead the load and a chain fall is hung from the hole. After the pad is no longer needed, the plate must be cut off, disposed of, and the attachment point ground smooth.
Another device employed in the prior art for lifting a load is a hoist ring with an attached bolt. The bolt is generally attached to the load or to overhead structure either by drilling and tapping a hole in the load or structure or by through bolting.
The prior art has several disadvantages. Welding a steel plate to or drilling and tapping a hole in the overhead structure or load requires at least two trades: riggers, welders, and/or machinists, and involves a considerable amount of time. If the overhead structure is a high strength or specialty steel, as is often the case in shipbuilding, additional time and cost is required for preheating and inspection. Drilling and tapping a hole in overhead structure will leave a hole that must be plugged and welded once the lifting point is no longer needed. This method is unsuitable when overhead structure is too thin to drill and tap without significantly affecting its structural integrity.